Dupe BluetoothSettings and DeviceListPreferenceFragment

Create the obsolete version of the belowing fragments, so we could
flip between old page and new page.

BluetoothSettingsObsolete and DeviceListPreferenceObsoleteFragment
contains all the old logic but:
1. Logic about BluetoothPairingPreferenceController(ag/2239482),
since this preference shouldn't be checked in without the flag :(

This cl also adds logic in MasterSwitchPreferenceController to flip
these two pages.

Following cl will refactor these fragment to make it compatible
to new framework.

Bug: 35877041
Test: RunSettingsRoboTests
Change-Id: I1cc1bc2d49d8a3e11c3127e56f6409fbc84028d8

src/com/android/settings/bluetooth/DevicePickerFragment.java

@@ -40,7 +40,7 @@ import java.util.List;
  * BluetoothSettings is the Settings screen for Bluetooth configuration and
  * connection management.
  */
-public final class DevicePickerFragment extends DeviceListPreferenceFragment {
+public final class DevicePickerFragment extends DeviceListPreferenceObsoleteFragment {
     private static final int MENU_ID_REFRESH = Menu.FIRST;
     private static final String TAG = "DevicePickerFragment";